The present invention generally relates to electrophotography and more particularly, to an image forming apparatus for use in an electrophotographic copying process, and an image forming method employed therefor.
Conventionally, in a copying apparatus employing a two or dual-component developing material composed of toner and carrier, it has been so arranged to maintain a toner mixing ratio constant in a developing material through successive replenishment of an amount of toner to be consumed by developing.
However, owing to the recent expansion in the application of the copying apparatus, there has been an increasing number of cases where photographic original documents, in which image portions occupy a considerably large area, are to be copied as well as original documents in characters, and when the images of such photographic documents are continuously copied in a large number, there are cases where newly replenished toner is not sufficiently mixed with the carrier so as to be fed for the developing as it is uncharged, thus inviting such problems as generation of fogging on the copied images, soiling of surrounding appliances by the toner scattering in dust, and reduction of the follow-up characteristic in the image density.